This invention relates to a method of lining pipeline also referred to as "sliplining".
"Sliplining" refers to a procedure of inserting a pipe or liner inside a pipeline by pushing or pulling the liner (typically made of plastic) through the inside of the pipeline (typically made of steel). In the pipeline industry sliplining a steel pipeline with a plastic liner is usually carried out to obtain the corrosive resistance advantage of the plastic piping system and the structural strength advantage of the steel piping system.
U.S. Pat. No. 4,496,499 teaches a method for lining high pressure pipeline with a plastic liner by first drawing the liner into the pipeline section by pulling the liner from one end area of the pipeline through the pipeline section until the liner is longitudinally co-extensive with the pipeline section. Before concluding the drawing step, a liner flange is affixed to the end of the liner opposite the end being pulled and then the drawing is completed to position the liner flange against a first pipeline flange. Then, the liner is longitudinally stretched within the pipeline section by elongating the liner without exceeding the elastic limit of the liner by pulling the one end area of the liner beyond the length of the pipeline section while the first liner flange prevents longitudinal movement of the opposite end of the liner along the pipeline section. After the stretching step, a second liner flange is affixed to the one end area of the liner segment opposite the first liner flange to position the second liner flange against a second pipe flange by permitting the liner to elastically retract into the pipeline section. A warm pressurized fluid is pumped through the liner to radially expanded the liner against the inside wall of the pipeline to an extant to permanently change the liner outside diameter from its original size to a size conforming to the inside diameter of the pipeline. A bleeder port is placed in pipeline section to evacuate the spaces between the liner and pipeline upon expansion of the liner by forcing air, water and other impurities through the bleeder port.
Using the method of U.S. Pat. No. 4,496,499 it is required to affix two flange members on each liner segment used for each pipeline section being lined. When several sections of pipeline are to be lined a multitude of flange points can exist along a pipeline route. There is a greater likelihood for leakage to occur at each flange point. Therefore, the more flanges used, the problem of leakage increases and for ecological and safety reasons it would be desirable to eliminate as many flange points along a pipeline as possible and provide a pipeline system containing a minimum number of flange points.
It is, therefore, desired to minimize the number of flanges used in a pipeline system when lining the pipeline and to provide a novel method of lining pipeline with a plastic liner.